In-situ grown polyaniline catalytic interfacial layer improves water dissociation in bipolar membranes

A catalytic bipolar membrane (BPM), comprising a pair of laminated anion-cation exchange membranes and catalytic interfacial layer, can efficiently dissociate water to in-situ produce acid and base in photo-electrolysis and electrodialysis processes. Many organic-inorganic catalytic interfacial layers show good water dissociation performance but encounter membrane failure during the water dissociation process due to critical layers’ delamination issue. Therefore, we hereby in-situ grow polyaniline interfacial layer (hereafter denoted as PIL) to simultaneously improve membrane durability and water dissociation performance due to electrostatic bonding and abundance of secondary amines NH in the PIL, respectively. Consequently, the produced PIL-BPMs accelerate the water dissociation by proton transfer reaction, which lowers transmembrane overpotential (1.87 V at 1000 A m−2) and water dissociation reaction resistance (7.44 Ω cm2) compared with the blank sample (2.82 V at 1000 A m−2 and 12.40 Ω cm2 water dissociation reaction resistance). While being used in a bipolar membrane electrodialysis, the resultant PIL-BPM has higher current efficiency (49.2%) and lower energy consumption (OH−: 1.01 kWh mol−1, H+: 1.05 kWh mol−1), compared with blank sample (current efficiency: 35.2%, energy consumption OH−: 1.50 kWh mol−1, H+: 1.61 kWh mol−1). Moreover, the PIL-BPMs also show ~2× greater stability due to the electrostatic bonding tactic than the blank membrane.